It's not everyday that you learn something - I've known for a while that a) OLED displays are supposed to be more power efficient than TFT and that b) the brighter the colours, the more power is actually consumed. But I hadn't realised the scale of the problem until now, with hard evidence from a semi-official Nokia source. Read on for links and quotes. Summary? On a OLED-screened smartphone, a pure white theme uses 14x as much power as a pure black one!

On the OLED screen, I can understand why having a darker screen (primarily black) would reduce power usage - the screen only lights up those pixels in use.

However I'm at a loss to explain the effect on the traditional LCD. The backlight is on permanently, and the LCD just filters/allows through differing amounts of light at each pixel - one of the reasons why LCD TVs don't tend to be capable of doing totally black blacks - they're normally just a very dark grey.

On the OLED screen, I can understand why having a darker screen (primarily black) would reduce power usage - the screen only lights up those pixels in use.

However I'm at a loss to explain the effect on the traditional LCD. The backlight is on permanently, and the LCD just filters/allows through differing amounts of light at each pixel - one of the reasons why LCD TVs don't tend to be capable of doing totally black blacks - they're normally just a very dark grey.

Interesting though!

Possibly the crystals in LCD are opaque (black) in their default state, and it requires power to turn them to allow colours through.

As for the OLED "discovery" NO SHIT SHERLOCK. Has nobody else ever played with the power monitor app and noticed this already? And not been particularly surprised. It's already a well known situation in the backlit LCD vs plasma tv power consumption world too.

As for the OLED "discovery" NO SHIT SHERLOCK. Has nobody else ever played with the power monitor app and noticed this already? And not been particularly surprised. It's already a well known situation in the backlit LCD vs plasma tv power consumption world too.

Jesus, who rattled your cage?

As someone who does not have a phone with an OLED screen it's an interesting article, as a factor of 14 difference in power consumption IS interesting to hear about, even if you clearly don't think so.

Now, if you didn't know before that an object generating a lot of light uses more energy than the same object generating none, then clearly you need to know.

Perhaps you could try leaving your all your house lights and electrical appliances on for one billing period and compare the cost to a period when they have all be been left off. You'll be amazed to find that they are more expensive when they are on!!

@ clonmult . The older LCD's are using CCFL type of lights . Normally with a constant light beam . With LED , backlight and edge , it is possible to dim the light on dark sides of the page . However not all LED screens are provided with this tech . The advantage is clear : darker spots , where the actual color is black or dark colored . This could explain also some energy saving . The scheme in Steve's article just shows two different screens . This is limiting drawing a general conclusions about screens , but for sure interesting .

@ clonmult . The older LCD's are using CCFL type of lights . Normally with a constant light beam . With LED , backlight and edge , it is possible to dim the light on dark sides of the page . However not all LED screens are provided with this tech . The advantage is clear : darker spots , where the actual color is black or dark colored . This could explain also some energy saving . The scheme in Steve's article just shows two different screens . This is limiting drawing a general conclusions about screens , but for sure interesting .

LED TVs do have a different backlighting technology to traditional LCD screens, but OLEDs don't have a backlight - its individual pixels that are turned on and off, and have their "own" individual lighting.

Totally explains why an OLED set to a black screen uses less juice (it also explains why the clock screensaver on the N85 looked so damn good).

Still doesn't explain why an older LCD, with constant backlight, would use less juice when set to a black screen, as the CCFL would be pumping out the same amount of light continually, just being filtered out as completely as the LCD shutters will allow.

Does it mean that OLED screens are actually less efficient for internet browsing since web pages very often have white background (e.g. AAS)? Itís quite an issue in my opinion since I spend much more time reading web pages than staring at the homescreen.

Would have been interesting to see the power usage of actual home screens, since presumably nobody has a theme with white text on a white background (or black on black). The difference would obviously be smaller in the real world, but would be interesting to see how much.

You know, I always noticed that I had worse battery life on my OLED screens than I did with regular LCD (N85, N86, etc), but just figured it was something stupid I was doing, cause *everyone* knows that OLED is more power efficient than LCD. Thanks for pointing out some great research, Steve! I don't recall what theme I used on either of those phones, but I typically prefer the lighter theme, so that's likely a huge factor.